Physiological measurements collect data for various processes occurring in a living body. For example, an electrocardiogram (ECG) measures electrical potentials produced through cardiac activity at the body surface and may be used to interpret various aspects related to cardiac activity. Bioimpedance is a measure of the resistance of living tissue to a current driven through the tissue and may be used to determine blood volume pulsed through an artery. Temperature may also be measured at the body surface and may be indicative of general health.
One challenge faced when making physiological measurements is noise introduced by non-physiological influences. Motion of the human body is one source of such noise. For example, an ECG reading is typically acquired using electrodes placed on a user's skin. A motion artifact is noise that results from motion of the electrode in relation to the user's skin. In some cases, movement of the electrode deforms the skin around the electrode site. This deformation causes a change in the electrical characteristics of the skin around the electrode and may contribute to the ECG reading. This contribution is not related to cardiac activity and thus is a source of noise. Motion artifacts are particularly relevant for physiological measurements in a mobile or portable application. For such applications, a high level of noise may be introduced by motion artifacts.
Accordingly, what is desired is a system and method to aid in accounting for noise such as motion artifacts in physiological measurements, particularly in portable applications.